Remote control receiver



Jan. 31, 19% K. B. AUSTIN REMOTE CONTROL RECEIVER 6 Sheets-Sheet 1 Filed Oct. '7, 1944 MK Q31 $33K Emioi. us twin l I I l l l I l l I l l i l i l l I l l I I l I I l 1 I QW M I I I I mgfiuwt k l-nvento'r': Kir'bg B.

AuS in,

His Attorney.

Jam 3E, 39% K. B. AUSTIN 2,495,915

REMOTE CONTROL RECEIVER Filed Oct. 7, 3.944 6 Sheets-Sheet 2 Fig. 2.

Inventor: Kirby- B. Austin,

His Attornes.

Jan. 31, 1950 K. B. AUSTIN 2,495,916

REMOTE CONTROL RECEIVER Filed 00'? 7, 1944 6 Sheets-Sheet 3 MHF one-H4708 [F 27 Fig.

VOL 0/75 inventor:

Kirbg B. Austin,

H i S Attorneg.

Jan. 31, 3950 K. B. AUSTIN 9 9 REMOTE CONTROL RECEIVER Filed on. 7. 1944 6Sheets-Sheet 4 His Attqr'neu. I

v M M E2350 $532 Emit; W he twin E 9313b Inventor: Kirbg B. Austin,

o kmbmtl um Jan. 31, 1950 KB. AUSTIN REMOTE CONTROL RECEIVER 6 Shets-Sheet 5 Filed Oct. 7, 1944 Inventor: Kirba B. Austin,

by Z 4) 1 Hi2 Attorney.

Jan, 31, 1950 K. B. AUSTIN 2,495,916

' REMOTE CONTROL RECEIVER Filed Oct. 7, 1944 6 Sheets-Sheet 6 Fig.7

; sz p y A) A 342 ass 335 534 93 as as Inventor:

Kirby B. Austin,

by if??? 67 Act orneg.

Patented Jan. 31, 1950 UNITED STATES PTENT OFFICE REMOTE CONTROL RECEIVER Kirby B. Austin, Bridgeport, Conn., assignor to General Electric Company, a corporation of New York 'Application October 7, 1944-, Serial No. 557,670

Another object is to provide means whereby the receiver may be controlled in all of its operations at each remote point, while each remote 12 Claims; (01. 250-20) to a desired frequency,

means at one station during the cycle of operpoint is provided With means to seize control of the receiver at any time, and irrespective of whether or not the receiver is being operated at the time from another remote point. In this way an operator at any remote point, requiring the use of the receiver, may'seize control of it irrespective of any use that any other operator may be making of it. I

Another object of my invention is to provide improved and reliable indicating means at the different remote points to indicate whether the receiver is energized and what remote point, or station, has control of it.

A further object of my invention is to provide means for selecting, at one or more remote stations, any one of a plurality of frequencies predetermined in the receiver, with a minimum of operations and a minimum of attentionon the part of the operator. In accord with my invention such selection is effected by a single operation on the part of the operator consistingin moving a knob, or dial, to a position corresponding to the frequency to be selected in which posi-- tion it may be released and the selection of the corresponding frequency automatically and reliably follows.

Another object of my invention is to provide reliable indication of the frequency selected at the remote point at which such operation is effected. v r

A further object of the invention is to secure these results at any of a plurality of stations,

notwithstanding that only one remote station is connected to control the frequency selecting means at the receiver at any one time, and the control of the receiver is alternatively switched from one station to another.

Another object of my invention relates to improved means for tunin the receiver to predeter mined frequencies from such remote points and to prevent tuning of the receiver to undesired frequencies. It sometimes happens in the remote control of such receivers that an operation is effected at a remote point to initiate a cycle of operations at the receiver to tune the receiver when during the cycle, and before its completion, an operation is effected at the remote point calling for tuning of the receiver to a different frequency. This operation may be affected by change in the control ations at the receiver, or it may be caused by a second station seizing control of the receiver during the incompleted cycle of operations, the second station being adjusted to call for the second frequency. An object of my invention is to provide means at the receiver to assure tuning to the selected frequency irrespective of the operations at the remote station or their occurrence in the cycle of operations at the receiver.

An object of my invention is to provide means to complete any cycle of operations at the receiver that is once called for from the remote station having control of the receiver irrespective of any operation that may occur at the remote station before the cycle is completed and irrespective of'any change in control of the receiver from one remote station to another. A further object is to provide means operative to tune the receiver to a second frequency only after the previously initiated cycle of operations is completed. In this way any tunin cycle once initiated is completed before any second tuning cycle can be initiated. This assures against tuning to any false frequencies not called for by operations at any remote station having control of the receiver.

Further objects of my invention will be understood'from' the following detailed description of my invention.

" The novel features which I believe to be char acteristic of my invention are set forth with My 111- particularity in the appended claims. vention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing in which Figs. 1, 2, 3 and 4 taken together, Figs. 1, 2 and 3 being positioned side by side from left to right in that order and.

Fig. 4 being positioned below Fig. 1, represent an embodiment of my invention; Fig. 5 represents an exploded view of a part of the tuning mechanism shown in Fig. 4; Fig. 6 represents an elevation view of this tuning mechanism; and Fig.

band of frequencies extending, for example, from 190-2000 kilocycles. I shall designate frequencies in this range as intermediate frequencies, or by the characters I. F. If desired this range of frequencies may be covered in three separate hands by the use of band change means later to be indicated.

In Fig. 2 I have represented by rectangle 2 a second similar receiver adapted for higher frequencies, which I designate as medium high frequencies (M. H. F), as for example frequencies extending from 2000-18,100 kilocycles, this range being covered in four bands by a band switch mechanism.

These two receivers may be carried upon an aircraft and are arranged for reception of various types including, for example, reception .in the various bands as desired, and including both continuous wave telegraphic reception and continuous wave voice reception. They are adapted to be tuned automatically to any one'of a number of predetermined frequencies, which may be 'selected by the operator by operation of a suitable switch device. These frequencies may be in any of the bands covered by the respective receivers. The receivers are also arranged to be manually tuned to any frequency throughout any of the ranges. These various types of'operation may all be efiected by remote control from stations positioned elsewhere -in the craft remote from the receivers.

These'remote control stations'may, for example, comprise an operators station'designated by the legend Operator in Fig. 3 and a pilots "station designated by the legend Pilot in Fig. 3. 'Eachof these'stations comprises two 'control boxes .3 and -'4 at the operators station, and5'and 6 at the pilots station. The control box 3 at the operatorsstation, and control box 5 at the pilots station, each bears 'the'legend M. H. F. since it is arranged to control the medium high frequency receiver 2 when'connected thereto through a relay 38. shown in'Fig. '2. This relay bears the'characters M. H. F. since it controls the connectionsof the M. 1H. F. control boxes 3 and 5 to the H. F. receiver. This relayis a two-position multiple contact relay arranged in one position to connect the operators M. H. F. controlbox 3:to the receiver and in the other position to connect the pilots F. control box 5 to the receiver. It operated to its different positions by respective :operating coils-O and P controlled by push buttons32'in the respective operators and-pilots control boxes 3 and 5.

The control box li'atthe operators'stationand the control box 6 at the'pilots station bear the legend I. F. since they control the intermediate frequency receiver 1. These-control boxes are arranged to be connected alternatively to control receiver I by a two-position multiple contact relay 39 shown in Fig.2, this relay being similartc relay 38 and arranged for operation to its two po-.

sitions by push buttons 32 in the -I. F. control boxes at the operators and pilotscontrol stations.

These control boxes 3, 4, 5 and 6 are all essentially the same in their circuit structure and accordingly the complete circuits of only one is shown, namely, that of control boxB. Each control box has a rotatable dial indicated at l, which may be rotated to various positions corresponding to the different types ofreception provided. This dial has properly.positioned'thereon, as shown in the control box l, indications of the different types of reception provided, and its periphery cooperates with an index 8 by which is designated continuous wave telegraphic communication,

which is telegraphic reception without automatic volume control and with the use of a local beat oscillator; and modulated communication, which is audio or voice modulated reception with automatic volume control.

The "three sectors, other than the preset" sector,-are'marked .Manual meaning that when theidialtis adjustedto these positions'the receiver is'tunable manually by operation of hand cranks H9 01-120 associated with the respective control boxes 4 .andiB.

The outer periphery of the three manual-tuning sectors-of the control dial are marked with characters indicating the frequency band in which reception is had'whenthe-dial is adjusted to therespective positions.

The outerperiphery of the preset sector of dial 1 .is marked with three legends, Mod, fC.'W.; and Bean, referring respectively to voice reception-telegraphic reception and bearing reception. The latterreception maybe with a re. tatable-loop antenna shown at the left sideoi Fig. 1 of the drawing.

'ThiS'.di8.1:T is arranged to rotate anumber of contact arms Ni, ii, l2, l3 and i4, shown in'the control box 6, which are elIective to control the receiver to'bring a'bouls reception of the type inclicated in the corresponding position on the control dial 1. :Each of 'these arms is rotatable with thedial-over a respective bank of contacts arranged in 'a circle. The circuit connections effected by' these arms'in'their different positions will later-be indicated in detail.

:Each control box also has a'further dial l5, operable to ten difierent positions in accord with predetermined stations, or frequencies, to be received. This dial'is provided with three contact arms IE, IT and I8 '(shown in box 5 of Fig. 3) which operate, through means'later to be described, to cause the receiverto be tuned to the desired preselected frequencies, or stations.

Each box also has a volume control knob 49, which has a pair of contact members 22 and 23, which operate over-respective volume control resistors or potentiometers 24 and 25. These contact'arms 22 and 23 are mechanically connected for unicontrol, as-indicated by the dotted line 26.

Each control box also has a control knob 27 which carries a contact arm 28 operating over a resistance 29 to 'efiect fine tuning of the receiver in'a manner later tobe indicated. Each control box also has a switch 9 to control the reception frequency band width of the respective receiver and a jack 3| in which headphones may be plugged for reception of signals.

Control box 6 has a switch, which bears the legend'Loop switch, which when operated energizes a relay designated'Loop relay as shown in the upper left-hand corner of Fig. l to disconnect the vertical antenna 20 from the receiver and connect thereto the loop antenna 2| shown in Fig. 1.

Each control box is also provided with a blue light designated on the drawing by the legend Blue and a red light designated by the legend Red, the blue light when energized being arranged to indicate the particular control box which has control of the receiver, and the red light'when energized indicating that the particular receiver is energized for operation.

The two-pole On-Ofi switch 30 provided in each control box is connected to energize and deenergize, in accord with the position thereof, the respective receiverwhen the control box has control of the receiver. Each control box is so connected and arranged that the operator at any control station may at an time seize control of the respective receiver, irrespective of what'reception the operator at the otherstation may be having at the particular instant, simply by operating his own push button 32. Of course if his On-Oif switch is in the off position, then the operator taking control of the receiver must energize the receiver by operating his own On-Off switch to the on position. Push button 32 is operative at all times irrespective of the position of the On- Off switch 30.

: These control boxes are connected to their re "spective receivers through a junction box represented by the dotted rectangle 33 in Fig. 2 to which the different control boxes 3, 4, 5 and 6 are connected by respective multiconductor cables 34, 35, 36 and 31. This junction box 33 includes the two two-position multicontact relays 38 and 39 previously referred to. It is connected to the two receivers through respective multiconductor cables 40 and 4| and it is connected through a further cable 42 to a dynamotor unit 43 comprising a motor 44 and a generator 45, the first of which is arranged to be energized from a source of operating potential 46 carried by the craft and when energized drives the generator to supply anode operating potential to the discharge devices in'the different receivers.

: The relays 38 and 39 each comprises a drum 52,

or 52, carrying along its length a group of conducting segments 53, or 53', arranged in parallel spaced relation, each about a portion of the circumference of the drum. These segments are continuously engaged by respective contacts a, b, 0, etc., each of which is continuously connected either to the respective receiver or'to equipment common to the two receivers. Thus, as shown, contacts a and b are connected through conductor 54 to the power source 46. Contacts 0, d, e, and others, as indicated by the brackets 55 and 56' are connected through conductors in the respective cables 40 and 4| to the respective receiver.

Contacts 10 of relays 39 and 38 are connected respectively through conductors 55, or I25, to the dynamotor unit 43. These segments when in one position engage a further contact a bp, Cp, etc. connected to conductors extending to the pilots control box, and when in the other position they represented by brackets 51 and 58 joined by a single line 59. When the relays are in the position in which relay 38 is shownjsuch connections are made to the respective operators control box.

A number of these connections are represented by the brackets 60 and 62 joined by a single line 63.

The lower two segments 53, which ar engaged by contacts a and b, respectively, are included in circuits by which the relay is operated by its operating coils O and P in response to operation of push buttons 32 in the control boxes. These circuits also control the blue and red lights on the control boxes and the energization of the receiver. Ihese circuits will later be traced in detail. 1

The receivers, as has been indicated, are substantially alike in their circuit structure. The details of one of the receivers, namely, the I. F. receiver, insofar as they are pertinent to my present invention, are represented in Figs. 1 and 4. This may comprise a superheterodyne receiver having a radio frequency portion 13, an interme-' diate frequency portion 14, a detector i5, and separate audio amplifiers l5 and Ti for the operator and pilot, respectively.

The radio frequency portion 13 may includ a three-position band switch it operated by a hand switch motor 19 to select the frequency band in which operation is desired. This portion also includes the usual unicontrolled tuning condensers 82 operated by a shaft 83, which is driven by tuning mechanism shown in Fig. 4.

The intermediate frequency portion 74 of the superheterodyne receiver includes a relay 84, which may be characterized as the broad-sharp relay since it may be utilized to control the band width of the intermediatefrequency channel of the receiver.

The receiver also comprises a beat frequency oscillator I84, which is arranged to'be controlled from the different control stations over conductor 296 and when operative supplies oscillations through condenser I86 to the detector to beat with the intermediate frequency oscillations to produce an audible beat note which may be heard in the head phones, as in telegraphic reception.

It also comprises a diode rectifier I81, which is utilized for automatic volume control purposes under certain conditions of reception as will later be indicated.

The tuning mechanism, shown in Fig. 4, comprises a motor 85 having a shaft 85', which is connected through suitable reduction gearing 80, 8!, 99, 9! and 86 to a long gear 8'! which extends throughout the length of the tuning mechanism and which is operated whenever the tuning motor is energized. This shaft operates through a number of diiferent gear groups 88, 89, etc., each corresponding to a frequency to be selected, to drive a shaft 92, which is geared through gears 93 and 94 to the shaft 83 of the tuning condenser. Each gear group 88, 89, of which there may be ten, for example, is associated with an electromagnet 95, 96, each corresponding to a frequency to be selected and each of which, when energized, attracts an armature 91, 98 carrying a respective gear 99, into mesh with the gear 8'], whereby the latter gear operates through the respective gear 99 to actuate the respective gear group 88, 89 to drive the shaft 83 to select the desired frequency. The frequency is selected when the gears in the respective group jam, as will later be fully explained.

'When it is desired to tune the receiver man-- ually, the manual tuning electromagnet I02 is energized and also momentarily, for a purpose later to be indicated,clutch electromagnet I.

The manual tuning magnet attracts its armature I03, which carries a gear I04 into mesh with the long gear 81, whereby it is driven and, through gears I and )1, drives gear I08 the latter of which operates through a group of gears within clutch housing I99, similar to the groups of gears 88 and 89 to drive the shaft 92 and consequently gears 93, 94 and the tuning condenser shaft 83 to a position where the gears within clutch housing I09 jam. The time or position in their operation when these gears jam is determined by the position in rotation of gear H2 which forms a part of the housing I99. This latter gear H2 is arranged to be manually rotated about shaft 92in accord with the frequency to be selected by means of a worm gear H3, which may be driven through bevel gears H4 and H5 both of which cooperate wi h the bevel gear H6 on the worm gear shaft and both of which are connected through mechanical connections I I1 and I I8 with respective hand cranks H9 and I20 near, or mounted upon. the respective control boxes 4 and 6.

The operation of this mechanical tuning assembly may better be seen from the exploded view of Fig. 5 in which the gear group 89 is illustrated and in which the gears within the gear housing I09 are shown in detail. This Fig. 5 illustrates the armature 98 carrying the gear 99 into mesh with the gear 81, which extends throughout the length of the equipment and which is driven by the tuning motor. For clearness of the drawing only the right end of the gear 81 is shown thereby to avoid concealing the gears 64 and 65 of group 89, which lie-back of gear 91.

Gear 99 is continuously in mesh-with gear 64 and the latter is continuously in mesh with the gear 65, these latter two gears being arranged to rotate in opposite directions. Gear 64 meshes with gear 68, which rotates loosely about the shaft 92 in the direction indicated by the arrow thereon, and gear 65 meshes with gear 61, which similarly rotates about shaft 92 in the opposite direction.

Between these two gears 66 and 61 is arranged the disk 68, which is securely, but adjustably, attached to the shaft 92 carrying the gear 93 which drives the gear 94 and the shaft83 of the tuning condenser 82. This disk 68 has a projection 69 from its periphery and is positioned circumferentially in accord with the frequency to be selected by gear group 89. Between this disk 68 and the gear 69 are a number of washers, each having a projection from its periphery, these projections being indicated at I22, I23 and I24. There may be any number of these washers but the first washer carrying the projection I22 may be positioned within the gear 66. This gear ,66 has an inward projection I25. The washers carrying the projections I22, I23 and I24 are loose on the shaft 92 and the projection I22 is arranged to be engaged by the projection I25 and to be rotated thereby in the same direction as the gear 66. When it is rotated sufiiciently, the projection I22, which extends over the periphery of the next adjacent washer, engages the projection I23 and then the two washers are rotated until the projection I23 engages the projection I24 when the three washers are rotated. This continues until the projection I24 finally engages the projection 69 thereby causing the disk 68 and hence the shaft .92 to be rotated. During this time gear 61 rotates in the opposite direction and causes a similar pile-up of washers having corresponding projections I21, I28 and I29 which rotate in the opposite direction until finally the last projection I29 engages the opposite side of the projection 69.- When this happens the gears jam, rotation of shaft 92 stops leaving the condenser in its desired position corresponding to the adjustment of disk 68 about the shaft, and motor 85 stalls.

The stator of motor 85, as shown in Fig. 4, is so arranged that when the motor stalls it rotates clockwise against the tension of a spring I 32 08.118- ing an arm I33 carried thereby to operate three contacts I34, I35 and I36 into engagement. When this occurs, the tuning motor relay I31, shown just above motor 85, becomes energized and opens the energizing circuit of the tuning motor and the magnet 96. The receiver is thus tuned to the predetermined frequency selected by the energization of preset magnet 96.

At the right-hand portion of Fig. 5 is shown the group of gears within the housing I09, this group of gears comprising the gears I42 and I43 corresponding to gears 66 and 61 of group 89, and between which is located the disk I44, which is secured to the shaft 92 and which has a projection I45 from its periphery as did washer 60 of the gear group 89. Between this disk I44 and gear I42 is the group of washers I46, and slmilarly between this disk I44 and gear I43 is a group of washers I41. Thesegroups I46 and I4! of washers operate between gears I42 and I43 in exactly the same way as do washer groups I22, I23, I24 and I21, I28, I29 between gears 66 and 61 to drive the shaft 92 through disk I44, attached thereto, to the desired position where the gears jam as was described inconnection with gear group 89.

In this case, however, the position in rotation of shaft 92 at which the gears jam is not determined'by any adjustment of washer I44 about shaft 92, as is the case in connection with wash er 68, but by the position in rotation of gear H2 and the housing I 09, the disk I44 being permanently fixed on the shaft. It will be seen that this housing I09 carries the gears I48 and I49, which mesh with each other and which mesh respectively with gears I42 and I 43 all after the manner of gears 64 and 65 of group 89. By rotation of housing I09 the position of these gears I48 and I 49 is rotated about shaft 92 and about the periphery of gears I42 and I43. Of course during this rotation, gear I08, by which these gears are driven from gear I01, rotates about the periphery of gear I01. In this way the frequency selected by this group of gears I42, I43, I48, I49 is determined by the position in rotation of gear II 2, just as that selected by group 89 is determined by the position in rotation of disk 68 on the shaft 92. Of course, as previously explained, the position in rotation of gear H2 is controlled by worm H3 (Fig. 4) which is operated by hand cranks H9 and I20 through bevel gears H4, H5 and H6.

It will now be seen that the group of gears in housing I09 provides in effect one additional preset frequency, in addition to those provided by gear groups 88, 89, etc., and that this additional preset frequency is variable by the hand cranks at the control stations which rotate housing I09. During preset tuning the clutch magnet I05 (Fig. 4) is energized to decouple shaft 92 from this housing I 09 to permit free rotation of the shaft 92. This magnet operates through mechanical linkage I53, shaft I54, and clutch operating member I55 to operate clutch member I56 to the right, as shown in Fig. 5, thereby wlth- 9: drawing-pins i]; carried thereby from holes.158a gear H2 thereby; permitting shaft 92 and. clutch member I56 to. rotate freely; while; gear;

H2. and: housing I09- remain fixed position since gear H 2. is in mesh; with worm=.l l 3;.

Clutch operating member I55: is bifurcatedand: carries two inwardly projfiotingpi s. 16.2, which. ride; in agroove l 6-3 in clutchmember -l 5 6- thereby tooperate the. clutch member longitudinally on. a rsplined. portion. r59 of. shaft 92- wh l -p rmi tingitsfree rotation. with the. shaft.

When. changing frompreset tuning. to, manual tuning, the. clutch magnet is energized. only. long. enough; to permit. the. -motor 85- to! operate; shaft; 83. to; a position. corresponding to. the: ppfiitiorr im rotation of. housing, tfldand gear. i [2,, i e-., to: a; position. agreeing withv the. position;v of: the hand. cranks. This assuresagreement bet-weemthe; frequency calibration of. the hand. crank-stand; the: actual position of the tuningfcondenseri. Them the clutchinagnet is automatically deenergized, and pins l5? enter holes I58 locking the shaft 9:2to= thehousing tile. the tuning condenser can then be rotated bythe hand crank'for man ua-l tuning ofthe set to desired frequencies which may be accurately indicated by a calibration on' a-d-ial geared-to'the hand cranks.

\ Shaft: 92'is providedwith a gear:I12*whichmay: also be employed to operate any suitable indi cating device on the receiver to indicatethet're quency to which the receiver is-tuned.

The system-for controlling-thetuning mechanism includes, inaddition to the tuning-motor relay 1 31:, previouslymentioned, a two-position= relay- I13 designated Preset-manual relay. which is: operated to the a left by coil 1 ltforpreset tun ingand tothe-right by: coil 7 5 for manualtuning.. It also includes av .preset selector. switch: H6, which rotatesto any onetoften positions in. accord withthe adjustment of the preset frequency selector dial- 15' at the respectiv control' box thereby toselect the appropriate-'magnet 95, 96, etc., corresponding to the-desired preset frequency. This switch comprises threerotating contact arms H9, 638' and It! operated over respective: banks of contacts bymotorl 'l l whichiscontrolled. by. preset motor relay H8 Difi'erent contactsin thebank cooperating-with contact arm H9 are selectively energizedin ac cord with. the position of thepreset selector dial l 5- at the control station. Ifcontactarm- I1 9 engages an energized contact, voltage is supplied to: relay l l 8 which operates, through circuits-later to be described, to energize tuning mutant-5'. Thistuningmotor then operatestocomplete any uncompleted tuning operation after which motor i l becomes energized. Motor 11-1 drives the. selector switch H6 to a position where contact; arm H9; which is broadenough to engage simultanecusly two adjacent contacts, engages two adjacent contacts both of which are'deenergized'. Relay I18 then drops out, the motor l"l.T s tops,. and the switch I76 is left with its contact arms inposition corresponding to the desired preset. frequency.

in this position, arm l-Blselects the magnet 95; etc., corresponding to the desired'preset" frequency. Arm I80 selects the frequency band in which the selected frequency lies and operates through switches A, B, C, etc., andthe comniutator I83 to control band switch motor 'l9f to operate band selector switch 18 to the..position. corresponding to the desired. frequency band 7 better. understanding of the,systemmaa1 now- 1 this control box has control of the I. F. receiver andthe, red light. indicates that that receiver isenergizedl The blue light of the operator's I; F. c. ontr ol'box is deenergi'zed but the red light. is lighted. indicating to the. operator that the receiver, isv energized.

The, circuitoi the vblue light of the pilots. I. F. control. box extends from the battery 46 over. conductor. 54;, contacts a andla of. the I. F. relay 391 in the junction boxtfi', conductor l92, which extends through cable 3] to the pilotsI. F. con.-

troll box where it extendsthrough the blue lamp.

andl'eftwhandlcontact arm oiswitchtll to ground thereby. energizing theblue lamp,

The energization of the receiver is brought.

about by meansof a circuit whicl extendsirom the battery 46 through thecontacts b and b of. the I. F." relay,,conductor i 93, which extends. through. the. same cable 37' and thencethrough the right-hanolarm of switch 33;,conductor Hi4; which.ext'ends,baok through the cable 31 to the junction box and thence through. conductor 55,, which extends through cable.,42 to relay l' ,in' thedynamotor unit,.and throughrable into-the I; .E..r,eceiver tosupply the A operating voltage thereto. The red lamp of the pilots I. F. con,- trol box 6 is connected between conductor L94 andfground and is thus. energized. Conductor. l9i4..also extends from-the junction box through. cable.. 35i to the. red. lamp in the operators. 1.3.. control box. That lamp is, therefore, also, energized. indicating to the operator that the receiver is energized.

In the receivenl, the conductor 55, which. is. labeled +A. supplies. A. voltages,v or. cathode en ereizing, voltages,v to.,.all of the discharge devices. in the radio receiver includingv the. two discharge. devices l.84. andv [81,, the heaters. 19M and I-96..of which are connected in seriesbetween. conductor. 55. and; ground. ihi's conductor also extends.

throughlarnp I-9,1I to.ground, whichlamp is ener gi'zed to indicate thatthe receiver isin'operation and. to, provide illuminationoi its dial- Conductortfiis. also connected to. contact. 1.3.4 of the. tu ning..moter stator assembly thereby to bring. about the: operation of the. tuning motor relay. iii-l henthe tuning motor stalls as above described.

Relay l S5... ofl the dynarnotor. unit. energized.

through; the. above. described circuit and closesa circuitfor the. motor44- through its: contacts.

and. conductor 1 98; extending to. battery. 46. Motor-'44; thus operates and. drives generator 45;. which develops anode operating potential bee wee ad c q an er rndhi co cr ton-J89 extends. through cablelz and. thence. through-both cables 4} and 41; to thett wo receivers.- l. and 2.. -I.n the rece iver. I: the. conductor. I99, whichis designated:l3+ extendst the R. E.

and A. portions. of the'receiver to supply anode. cperating potential to the anodes of. the; discharge. devices employed: therein. It also supplies, operating potential to the beat oscill a.-- tor; i 84. .and bias potential tothe cathode of diode- I-SJ; to. render that device. non-conductive.

While this ..B potential. is supplied; also; tor-re..-

ceiver 2, A potential is not now supplied thereto and that receiver is therefore inoperative.

All of these circuits are controlledby the pilots On-Oif switch, which completes the circuits of the red and blue lights, the filament and dial lamp circuits in the receiver, the automatic tuning mechanism, and also that of relay I95 in the dynamotor unit. Relay I95, in turn, energizes the motor 44 thereby energizing the receiver.

The pilot may now by operation of the controls on his control box control the receiver I to effect the reception he desires. The operator has no control of the receiver since his box 4 is disconnected therefrom by relay 39. He may seize control of it, however, at any time by simple operation of his push button 32. This push button closes a circuit which extends from ground through the contacts of push button 32, conductor 202 in box 4, which extends through cable 35, coil of relay 39 and its contacts u and a to conductor 54 and battery 46. Coil O operates I. F. relay 39 to its opposite position thereby disconnecting box 6 from the receiver and connecting box 4 to control the receiver. At the same time the circuit from coil 0 to the operators push button is opened to prevent damage to the coil should he continue to press the button for any reason. The operator thus acquires control of the receiver and the pilot loses control until he operates his push button 32 to again seize control. The operator now, to maintain the receiver energized, must close his On-Oif switch since the energizing circuit of the receiver now extends from battery 46 through conductor 54, contacts b and be of the relay, conductor I93 of cable 35 and thence through the right-hand contact arm of the operators On-Ofi switch, and conductor I94 back to conductor 55 and relay I95 in the dynamotor unit;

Both red lights, of course, are lighted but the blue light of the pilots box is now extinguished since its circuit is broken atcontacts a and u of relay 39. The blue light at the operators box is lighted since its circuit is completed at contacts a and an of relay 39.

In this way either the operator or the pilot may seize control of the receiver at any time irrespective of what operation the other may be having and the signal lights indicate correctly the condition of the apparatus.

Of course, this same operation is had from the M. H. F. control boxes 3 and 5 through similar circuits, which are now obvious from the drawing, the only difierence being that relay I95, rather than I95, in the dynamotor unit is operated to energize motor 44. Conductor I26 of cable 4I carries operating potential to receiver 2, just as did conductor 55 of cable 40 carry operating potential to receiver I. These conductors are connected respectively to the high voltage terminals of the windings of relays I95 and I95 so that if either receiver is turned on by operating switch 30 on whichever control box has control, the dynamotor operates to supply anode operating potential. Further either the operator or the pilot may operate and receive signals from both receivers at the same time by operation of both buttons 32 and the On-Ofi switches 30 in the control boxes of his respective station. This is of advantage in that either of the receivers may be energized or deenergized from either station without aid from the other station. For example, let us suppose that the operator about to leave the craft, for example, observes that one of his red lights is lighted while his On-Oif switch for that receiver is in the 01f position. This would of course mean that that receiver is energized through the pilots box and that that box has control of the respective receiver. He may know that the pilot has already left the craft. He may, however, deenergize the receiver, without going to the pilots station, by pushing his push button 32 to seize .control of the receiver. Since his On-Ofi switch is already in the off position, the receiver is deenergized and all lights are extinguished.

The provision of separate relays I and I95 in the dynamotor unit makes possible the reliable control of the motor from all the difierent control boxes with a minimum of equivalent and without undesired sneak circuits causing faulty operation of the equipment. At the same time this arrangement provides circuits which may be adequately fuse protected by fuses 23B, 231 and 238 at the junction box.

Predetermined frequency selection Assuming that the apparatus is in the position shown and that the pilot desires to receive modulated signals, as for example voice, from a station which the receiver is adapted to select by preset tuning, he operates the dial 1 to the position shown in the drawing whereupon the contact arms I0, II, I2, I3 and I4 occupy the position illustrated. Arm I0 connects to ground a conductor 203, which extends through the cable 31 to the junction box, thence through contacts 0 and Cp on the I. F. relay 39 and conductor 203 of cable 40 to the I. F. receiver, and thence through the coil I14 of the preset-manual relay to the +A conductor 55. Coil I14 thus operates the several armatures 204 to 201 to the left, as shown in the drawing, to adapt the receiver for automatic tuning to a predetermined frequency corresponding to the position to which the preset frequency dial I5 at the pilots control box may be operated.

Armature 206 of preset-manual relay I13 completes an energizing circuit for clutch magnet I05 whichoperates to withdraw pins I51 from holes I58 (Fig. 5) in the clutch housing thereby to permit shaft 92 of the tuning mechanism to rotate freely while the clutch housing I09 remains stationary since it meshes with manual tuning drive worm I I 3.

, Arm II, operated by the control dial 1, connects all of the rotary contact arms I5, I1 and I8, operated by the preset frequency dial I5, through conductor 208, which extends through the cable 31, and contacts 10 and p on the I. F. relay, to the +Abus 55. These contacts I6, I1 and I8 thus have impressed on them the potential of battery 46. Contact arms I6 and I1 operate over contacts I to I0 of respective banks of contacts 2I2 and 2 I 3, each of which includes twelve contacts. They are prevented from'engaging contacts II and I2 of these banks by stops '2 I9. Contact arm I8 ope'rates over the bank 2I3 and is positioned diametrically opposite contact arm I1.

The difierent contacts of these banks 2I2 and 2I3 are connected through five conductors 2I4, 2I5, 2 I5, 2 I1 and 2 I8, which extend through cable 31, to the junction box where four of the five conductors may be' traced through corresponding contacts on the I. F. relay, the fifth conductor 2| 5 being common to the corresponding conductor from switch I5 in box 4 in cable 35 and not requiring switching by the I. F. relay. The five conductors then extend through cable 40 to contacts in the circular bank I66 of a motor driven 76 preset selector switch I16 with which cooperates: the rotary con'tactarm: I19; :As previously: stated, this contact arm l 19 -is operated in unison with the other contact arms of the switch; I16 and is connected toground through the winding of 'relay I 18. This contaotvarm I19 is sufiiciently wide to contact any two adjacent contacts inthe. bank I66 and the contacts of this bank are so wired through the conductors 2I4 to.2I.8 to the. contacts. of the banks 2I2 and 2I3- at the control box that two adjacent contactsiin the bank- I66.

are-d'eenergized. for each position of the contact;

arms I6 I1 and" I8 of the preset frequency switch Other contacts may bedeenergized, butin not case are more than twoadjacentcontacts die-- energized and the two adjacent contacts which arev deenergizedare positioned about the bank in accord with the position of the arms. I6, I1 and I18, and: hence in accord with the frequency to be. selected.

For example, with switches I6, and I8 in the; position shown, voltage is supplied from the. conductor 208 through contact arm II- and the, contact arm I6 to conductor 2I4, through arm l-Tito conductor 215, and through. arm IB-to conductor 216; Novoltage is. supplied to conductors 211: and. 218'. When: conductors 2l4, 2I5 and 216 have; voltage impressed thereon, voltage exists on contacts. I, 2, 3, 5, 8:, I0, II and I2 of bank I66 ofswitch. [16, the last contact I2 being connected directly to the +A. bus.. Contacts 6 and 1 are the onlytwo adjacent contacts which do not have voltage applied thereto. Contact arm I19 is shown inengagement with these two contacts and hence relay I18, which is'connected thereto, is shown in its deenergized position.

Let us suppose that the pilot. now desires to select preset frequency No.3. He operates the. dial. I5 to the position where contact arms l6, l1 engage contact 3 in their respective banks and. contact; arm I8- engages contact. 9 in bank 2I3. Then voltage is supplied through contact arm I6. to conductor 2I8, through arm. I1 to conductor 2 I 5, and through arm I8 to conductor 2 I4. These. conductors apply voltage to. contacts I, 2, 5, 6,. 8, 9 and II of bank I65 leaving adjacent contacts 3 and 4 deenergized. Relay I18 is thus immediately energized and operates its contacts to the right. In operating its left-hand armature 224 to the. right, this relay momentarily breaks a holding circuit for tuning motor relay I31, which drops out breaking the circuit for preset motor I11 at armature 223. Thus the preset motor does not immediately operate.

This holding circuit for relay I31 extends from the +A bus 55 through the left-hand armature 224 of relay I18 in its left-hand position, armatures 295 and 294 of the preset-manual relay, and armature 223 of the tuning motor relay in its right-hand position and thence through the winding of the tuning motor relay I31 to ground. The. tuning motor relay therefore is deenergized and operates its armatures to its left-hand positionwhere its contact 223 completes a circuit for the forward winding I85 of the tuning motor 85. This. circuit is the same as that previously described extending from the +A bus 55 through the left-hand armature of relay I18, armatures 2-95 and 204 of the preset-manual relay, armature 223 of the tuning motor relay in its lefthand position and thence through the forward winding I85 of the tuning motor 85. The tuning motor then operates until one of its gear groups jams, as previously described,:if its gears are'not. already jammed, when the motor stalls and its stator-tends to rotate againstthe spring 32 thereby operating *arm; I.3.3:into engagementwith;

contact I234: and causing the contacts- I.34, I35 and I.36:ai1=-to1,engage. Voltageis then supplied; from the. +A. bus. 55. through contacts; I34 and IE5 tothe tuning: motor relaymausingitxto enen-'- gize. and:- break the circuit; of. thetuningmotorat its. armature 223.: in. its; lefteha'ndi positionand to. close again; theabove tracedi holding. circuit,

for-itself by this; armature 223 .in'its. right hand; position.

The preset. motor; is: now. connected; directly across relay. I31. through rightrhand armature;

225 of relay I18 in its right-hand positionand;

thismotor H1 is thusener-gized and rotates;pre-

set. selector switch L16 until contact; arm; I19; engages theetwo adjac n deener izedz c ntactss 3; and 4 of, its refipective bank; Relay I18 is; then. deenerg-ized and; drQpsxout, Its left-hand: rmatur a ain momentar ly; inter p the hold.-

ing circuit of tuning motonrelay I31; and; that;

relay. drops out, again;; energizing the tuning; motor. This; time, however, contact arm l8] Of switch I16 is in engagement withcontact3 otits. respective bank I64. thereby energizing preset? tuning magnet 95 through a circuit which eX- tends; fromv ground at, the. rightrhand-armature;

291; of" the presetrmanual relay, throughcontact. arm; I8I- on its thirdcontact winding of preset tuningv magnet-9 5, left-hand armature, 223. of, the-.- tuning motor relay, armatures 2Il4-andI 295 of the preset-manual relay, and left-hand armae tune-r224 of the preset? motor relay. I-18 to; the? +A bus.- Tuning; motor now operates and. driyes the tuning; mechanism until the gears :oi.

group 8 .31am. This occursiwhenthe-tuning,con;-

denser shaft83 hasbeen operated; to the preset. position. corresponding to the frequency to. be, selected. The motor, then stalls and the;stator' againoper-ates contacts I34, I35 and I36 to energg ize'theltuning motor relay I31, which operates;

to interrupt the. forward. circuit ofthe motor.. Thusthe rotor. of the: tuning condenser 82, is. adjusted to receive thedesired frequency.

. Whenrelay, H8 is deenergized, due to-contact arm I19; engaging its contacts:3 and 4, it, by its,

right-hand armature, closes; a. circuit for. the;

band-switch motor 19, which extends from ground -atarmature 225 of. relay I18, through,

motor 19, brush 2-26 on; commutator I83, contact,

221, in. engagement with, this commutator, con tacts 228, 229 and. 232 of preset band selector 3,, conductor- 246, third contact of bank I65 of the.- preset selector switch, rotaryv contact arm I80,

armature 265 of the preset-manual relay, and.

armature 224 of the preset relay I18 to the +A bus,55. Motor 19 now operates, after motor. I11

hasgcompleted itsoperation, and. drives the band};

switch-1.3 and the; commutator I83 until the. non;-

conducting segment 233 engages contact 221.,

The motor: circuit is then broken and the band switch is positioned. at. the; desired band.

.Preset band selectors A, B, C, etc of which there-may. be as many as there are frequencies to. besselected by preset tuning,. are drums. eachof" which-has a contact. 229 permanently con-.

nected, as bya. slip ring .and brush connection,-

under the respective contact, thereby to stop the band switch in a position corresponding to the band in which the frequency to be selected lies.

The brushes 221, 248 and 249 are also connected through respective conductors 263, 264 and 265, which extend through cable 40 to junction box 33 and thence through cable 31 to control box 6 and cable 35 to box 4 where they are connected to different respective contacts of the bank engaged by arm I I of switch I in other positions. In this way the arm I I selects the band in which reception is had when the receiver is tuned manually.

On the shaft of the band switch are two additional contact arms 234 and 235 which establish certain circuit conditions desired in the different bands. These circuit connections will later be described in connection with the more complete description of circuits established by arms ID to I4 of the pilot's control dial 1.

It will now be observed that any deenergization of relay I31 energizes the tuning motor. This is true irrespective of the position of the presetmanual relay since the holding circuit for relay I31 extends through armatures 204 and 205 of this relay in either of its two positions. Any operation of this relay interrupts this holding circuit and energizes the tuning motor to complete any previously uncompleted tuning operation.

Moreover, any operation of relay I18 causes its left-hand armature to break momentarily the holding circuit of tuning motor relay I31 thereby to energize the tuning motor and to cause that quency dial I5 to any other one of its ten posi-.

tions. Relay 118 is immediately energized breaking momentarily the operating circuit of relay I31, which operates to energize the tuning motor, which immediately operates to a position where its gears jam, if they are not already jammed. Thereafter the tuning motor relay I31 is again energized and the preset motor I11 operates switch I16 to a position corresponding to the new frequency. Thereafter the band switch motor 19 operates to a position determined by the arm I80 of the preset selector switch and by that one of the preset band selectors A, B, C which happens to be in circuit with the particular contact selected by contact arm I80 of the preset selector switch. At the same time that the band switch motor is operating, the tuning motor operates the tuning mechanism to drive the unicontrolled condensers 82 to tune the receiver to the desired frequency. Of course, if the new frequency is in the band for which the band switch is already positioned the band switch motor does not operate.

The operation of relay I31 to energize the tuning motor at the beginning of each preset tuning operation, before any operation of the preset selector switch I16, has the important advantage that it compels the tuning mechanism to complete any tuning operation for which it is previously set before it can start a second, or new, tuning operation. In this way it avoids, or prevents, operation to false tuning positions. For example, let us suppose that the preset frequency dial I5 be set to frequency No. 3 and the tuning mechanism starts to tune the receiver to that frequency but before this tuning operation is completed the preset frequency dial is moved to frequency No. 10. If the preset motor switch I16 operated immediately in response to move- 16 ment of the preset frequency dial, then such mov'-' ing of the dial to frequency No. 10 would bring about the immediate deenergization of magnet 95 corresponding to frequency No. 3. This, however, would not necessarily disengage the gears of the group corresponding to frequency No. 3 from gear 81. tion of gears 81 and 99 and the following gear 15 such as to maintain engagement of gear 99. Some reversal of the motor, or at least of gear 81, is required for positive disengagement of these gears. quency No. 3 would continue to operate even after anew magnet corresponding to frequency No. 10 is energized. This energizing of a second magnet may cause two groups of gears to be driven simultaneously by the tuning motor. The result would be that the gears would finally jam with the tuning condenser shaft at a false position not.

corresponding to either preset frequency No. 3

or No. 10. In accord with my invention this re-.

ing motor relay and causing the tuning mechanism to operate to the new frequency.

The reversal of gear 81 to disengage any gears in engagement therewith after a tuning operation, is brought about by action of spring I32, one end I00 of which is anchored in a hub IIJI fixed on shaft IIII and the opposite end of which is anchored in gear 8! which is free to rotate on shaft IDI. Thus the tuning mechanism is driven through this spring which is under a certain tension during the tuning operation.

When the gears jam, shaft IUI and hub IOI' stop. Since the motor is still energized, gear BI is still driven and further tensions the spring until the motor stalls and its rotor stops. Torque, however, still exists in the motor and since the rotor cannot rotate, its stator rotates clockwise as shown in the drawing, closing contacts I34, I35 and I36. Tuning motor relay I31 then deenergizes the forward winding of the motor and spring I32 tends to rotate the rotor in the opposite direction. Since the rotor has inertia, some of the energy of the spring rotates shaft I 0 I, and hence gear 81, backwards thereby freeing any gears in mesh with it. This latter action is aided and rendered more positive by momentary energization of the reverse winding I85 on the motor. This is effected by contact I36, which is engaged by contact I 35, which in turn engages contact I 34 connected to the +A bus.

,To avoid damage to gear 80, 8I, 90, 9| and 86 due to inertia of the motor when the gears jam on reaching a preset frequency setting, gear is connected to the shaft of the motor through the friction connection shown, comprising washers engaging each side of it and pressed against it by spring washer 80'.

Automatic tuning to the preset frequencies indicated on dial I5 is had when arms II! and II. operated by the control dial 1, are on any. one of their three contacts I, 2 and 3 corresponding to voice reception, telegraphic reception, and bearing reception, as noted on, the dial 1.

This is because the direction of rota-,

Thus the gears corresponding to fre-v This is.

true since arm l maintains the coil I14 of preset-manual relay energized and arm II applies voltage to the contact arms of the preset frequency switch I5.

Manual timing When the control dial 1 is operated to any of its other positions, namely 4 to 12, manual tuning by means of the hand crank I20 may be had. Arm ID then connects to ground conductor 30 1. This conductor extends through cable 31, certain contacts of I. F. relay 39, cable 40 and through relay coil I15 of the preset-manual relay to the +A conductor 55. Relay I13 is thus operated to the right breaking momentarily the holding circuit for relay I31 causing the tuning motor 85 to be energized and to operate. Since none of the preset tuning magnets 95, 96 etc. are now energized the gears in the groups corresponding thereto are not operated by the tuning motor and do not jam.

Arm I l of the control dial 1 breaks the voltage supply circuit to the preset frequenc switch 15 and thus relay I18 is deenergized and remains in its deenergized condition. Arm 201 of the presetmanual relay connects to ground conductor 3B5 thereby completing a circuit through the manual tuning magnet 502, the left-hand armature of the tuning motor relay 131 in its left-hand position, armatures 2M and 2-05 of the preset-manual relay in their right-hand position and armature 224 of the prose motor relay to the +A con ductor. Thus manual tuning magnet H32 operates its arm Hi3 causing the gear its to engage gear 81 as proviously described. Clutch magnet M15 is now energized through a circuit which extends from ground through the operating coil of this magnet, right-hand armature of relay 931 in its lef -hand position, and arm 206 of presehmanual relay I13 to the +A bus. Thus the tuning motor now operates until gears within the clutch housing its jam, as previously described. The position of the tuning shaft 83 at which these gears jam is dependent, as previously described, upon the position in rotation of the clutch housing N9, which is controlled by the worm I 1-3, the latter be ing operated through bevel gears H4 or H5 and flexible mechanical drive connection H1 or H2 from the handoranks I I9 or 120. When the gears in housing 109 jam, the tuning motor relay I31 becomes energized, as before, and by its righthand armature interrupts the energizing circuit of the clutch magnet I05 thereby locking shaft 9'2 and the tuning condenser shaft 83 in position corresponding to the calibration of handcranks H9 and E29.

Thus the first operation of the tuning control system in response to operation of the control dial 1 to any of its manual tuning positions is to operate the tuning condenser to a position determined by the handcranks. This means that the frequency calibration of the handcranks then agrees with the tuning indicating mechanism (not shown) driven by gear I12 and located on the receiver. The pilot may now operate his handcrank 920 to tune the receiver to any frequency which he desires to select by operating his handcrank to a corresponding position on the scale cooperating therewith and which may be call" brated in terms of frequency. I

Since the preset-manual relay armature I13 is in its right-hand position, the circuit of contact arm I80 of the prese selector switch is broken at the left-hand contacts of the armatures 2M and 2B5 of the preset-manual relay. This means that nocircuit for the band switch motor 19 can be completed through the preset band selectors, A. B. C and the contact arm I and that the band in which the receiver operates is determined by the position of contact arm II on the control dial 1 which may engage any one of its contacts 4 to i2 thereby completing a circuit for the band switch motor. This circuit eX- tends from conductor 208 in the pliots control box which, it will be remembered is at +A potential, through arm H on the control switch in engagement with any one of its contacts 4 to 9, i! or I2 and thence through the respective one of conductors 263, 266 or 265 as the case may be, which conductors extend through cable 31, junction box 33, cable in to respective brushes 221, 248 and 2 39 of the commutator I83, brush 226, band switch motor i9 and armature 225 of the preset motor relay I18. Thus the band switch motor 19 operates until it rotates nonconducting segment 233 under that one of the brushes 221, N8 and 249, which is in circuit with the arm iI of the control knob. None of the conductors 263, 266, or 2'65 can be energized through switch 1 of box 4 since its conductor 2% is open at relay 3B.

As previously stated, any interruption of the circuit which deenergizes the tuning motor relay I31 causes the tuning motor to operate to a position where a gear group jams. This is important for the further reason that it means that the first operation of the system which occurs after operating the control dial 1 to a manual tuning position is to adjust the tuning condenser automatically to a position corresponding to the position of the hand crank I26. Thus the pilot knows by looking at the calibration which may be provided to cooperate with the hand crank I20, the frequency to which the receiver is tuned to respond. He may then tune the receiver to any desired frequency in the frequency band selected on dial l by simple operation of the hand crank to a caiibration corresponding to the desired frequency.

This is also important since it means that when control of the receiver is seized by the operator at the other control box, the first operation of the tuning motor system is to tune the receiver to the condition which is set up in that control box. Thus, for example, let us suppose that the operator at the operators station seizes control of the receiver by pressing his pushbutton switch 32 and that his control dial 1 is in a preset position and that his preset frequency dial I5 is on a position corresponding to frequency No. 3. Operation of his pushbutton'32 operates relay 39 at the junction box which in operating interrupts momentarily the holding circuit of the tuning motor relay. The tuning mechanism then operates immediately to tune the receiver to the preset frequency it was last set at, i. e. to complete any previously uncompleted tuning operation. Thereafter the preset switch I16 is positioned to the new frequency and then the tuning mechanism operates the tuning condenser to a position corresponding to frequency No. 3. If, on the other hand, the operators control dial 1 is in a manual tuning position when he operates pushbutton 32, then the tuning motor operates to tune the receiver immediately to a frequency corresponding to the position of his handcrank HS in a frequency band determined by the position'of his control dial 1.

This operation of relay i3? is also important in bringing about correct operation of the tuning mechanism after the receiver has been deenergized. Of course, dials 1 and I5 may be rotated to any position while the receiver is ofi. Deenergizing of the receiver itself deenergizes relay I37 and positions it to energize the tuning motor immediately upon energization of the receiver. It then operates to complete the tuning operation for which the system was last previously set and during which the motor may have been stopped before completing the tuning operation. The preset selector switch then operates to any new preset frequency position for which the control box may be set when the receiver is turned on. The tuning motor then operates to tune the receiver to the new frequency. If when the receiver is turned on the control dial is in a manual tuning position, due to having been changed when the receiver was off, the motors immediately tune the receiver to the frequency and band corresponding to the position of the handcrank and control dial 7, respectively.

It will now be seen that arms II and III of the pilots control dial 7 determine respectively the band in which the receiver is to operate and whether the tuning is manual, as by handcrank I26, or by automatic tuning to frequencies corresponding to the position of preset frequency dial I5.

The circuit changes effected by arms I2, I3 and I4 of the control dial 7 may better be explained after consideration is given to the audio circuits, volume control circuits, and beat frequency oscillator circuits of the receiver.

Audio circuits The low impedance audio output circuit of the cathode follower amplifier stage coupled to the output of detector 75 extends from that amplifier over conductor 254 of cable 46. This conductor 254 divides at the junction box and one branch 254 extends through cable 35 to the operators control box 4 and the other branch 254" extends through cable 37 to the pilots control box 6 where it is connected to one terminal of the volume control potentiometer 24, the opposite terminal of which is either grounded through arm I2 of the pilots control switch I in certain positions thereof, or is connected to ground through resistance 206 when arm I2 is in other of its positions. A variable contact 22 of this volume control potentiometer 24 is connected through a conductor 255 in cable 37, which conductor extends through the junction box and through cable 40 to the input of the first amplifier 266 in the pilots A. F. amplifier TI. The output from this amplifier is supplied through conductor 267 in cable 40 which conductor extends through the junction box and cable 37 to the pilots jack 3| into which he may plug headphones for reception of signals.

A similar circuit for the operator's control box 4 extends from the cathode follower amplifier output through conductor 254 and 254', the latter of which extends through cable 35 to the operators control box 4 where it is connected in exactly the same way that conductor 254" is connected in the pilots control box 6. The variable contact in the operators control box corresponding to contact 22 of the pilots control box is connected through conductor 255 in cables 35 and 4D to the input of the first audio frequency amplifier 268 of the operators A. F. amplifier 76. The output from this amplifier extends over a conductor 269 in cables 40 and 35 to the operators jack 3|. Thus two separate audio frequency channels are provided each of which includes an amplifier 76 or 77 in the receiver and a volume control on control box 4 or. 6 which may be manipulated by the operator and pilot, respectively at his respective control box. It is desirable that the detector have an output coupling stage of the cathode follower type since the output is of low impedance, thereby reducing the attenuation produced by the relatively high capacity of the cables connected thereto and makes possible the control of volume at the control boxes by potentiometers 24.

On the same shaft with the volume control contact 22 is a separate rotatable contact 23, which rotates over a resistance 25 to vary the volume by varying the radio frequency amplification of the receiver. This resistance is arranged to be connected between ground and the cathode of the radio frequency amplifier 273 of the receiver as a cathode bias resistor variable to control the gain of the receiver during reception of certain types. With the control dial 7 in the position shown this connection extends through conductor 275 in cable 37 through relay 39 and cable 49 to the upper contact 276 of the selector switch which is engaged by arm 235 when the band switch 78 is operated in the corresponding band. With this arm 235 in the position shown the circuit extends from this contact 235 through choke coil 277 to the cathode of radio frequency amplifier 273. The cathode of this amplifier is connected between resistors 270 and 272 which form a resistance path between the +3 bus I99 and ground. Resistance 272 limits the potential on the cathode and hence on the circuit to resistance 25 in the control box when the circuit is momentarily opened as during operation of relay 39 in the junction box.

The volume may also be controlled by movement of contact 23 when the band switch is adlusted for either of the other two bands if the control dial 7 is in any of its positions 2 to 9 where arm I4, operated-thereby, engages contacts of its respective bank which are connected to conductor 275. This arm I4 is connected through conductor 278 through cable 37, relay 39, and cable 40 to contacts 274 and 280 of the selector switch and thence through arm 235 of that switch to the cathode of the amplifier. However, if arm 235 of this switch is in engagement with contacts 274 or 280 and arm I4 of the pilots control dial is in any of its positions 11, 12 or 1, then the cathode of amplifier 273 is directly grounded and volume control contact 23 has no effect.

As soon as operation of the tuning motor and band switch motor is completed, signals are received by both the operator and the pilot in their headphones plugged in their respective jacks 3I and the volume may be controlled by either by operation of the volume control knob I9. However, if control dial 7 of the box that has control is in any of its positions 2 to 9 then volume control knob I9 of that box controls the sensitivity of the receiver while volume control I9 of the other box has no eifect on sensitivity but still controls the input to its corresponding audio amplifier.

Automatic silencing The two audio frequency amplifiers 76 and 77 are inoperative during operation of any of the motors 35, I77 and 79 and thus objectionable noise in the headphones during the tuning operation is prevented. The cathodes of the amplifiers 266 and 268 are connected together and through a conductor 279 to the common terminal of three resistances 282, 283 and 286 shown at the left side of Fig. 1. The opposite terminal of resistance 282 is connected to the high voltage terminal of motor E9. The opposite terminal of resistance 283 is connected to the high voltage terminal of preset motor relay its and the 0D- posite terminal of resistance 28d is connected to the high. voltage terminal of the forward winding Hi5 of the tuning motor 35. Thus when relay l 78 becomes energized suiiicient voltage is applied to the cathodes of amplifiers 26-5 and 258 to silence the receiver so that objectionable noises during operation or the tuning motor 85 are not heard in the headphones. The receiver is maintained silent thereafter during any subsequent operation of the tuning motor 85, the preset motor ill or the band switch motor is by the respective connections through resistances 284, and 262 to the cathodes of these arnplifiers.

During operation of the receiver, after the mo tors have completed their operation, the bias voltage between the cathodes of amplifiers and 2 58 and ground is determined by the net resistance of these circuits including conductor 2'53 and resistors 232, 2533 and 284 through the respective motor or relay windings to ground, since there is then no voltage supplied to the motors or relay H3.

Code reception During modulated communication, or voice reception, the beat oscillator iii i is inoperative. This oscillator 5853 has its control electrode con nected through an oscillatory circuit 29?, 365i and resistance 288 to ground, this resistance being bypassed for currents of the frequency at which the oscillator operates. Resistance 295i is apart of a bleeder circuit comprising resistances 25s and 392 between the +13 bus its and ground and 51:

its upper terminal is at high positive potential. The cathode of device its is connected to an intermediate point on the inductance 2 and is thus at the same high positive potential. This renders the device inoperative since the control electrode is connected to ground through resistance 3833 thereby obtaining bias voltage in excess of that required to cut-ofi' its plate current. During code reception, C. W. communication, the upper terminal of resistance 2% is grounded through conductor 2%, which extends through cable as, certain contacts on I. F. relay 39 and cable 3! to contacts 5 and i to 9 of the banks engaged by arm is of the pilots control dial '2. ihis lowers the cathode potential of device E82 allowing it to oscillate and supply oscillations through condenser we to the detector. These oscillations differ in frequency from the inter mediate frequency of the receiver by an audible amount such as a thousand cycles per second, which beat frequency is heard in the headphones during continuous wave telegraphic reception.

Automatic volume control The automatic volume control diode I87 has its anode connected through condenser 292 to the detector input from which it receives the intermediate frequency oscillations of the receiver. This anode is also connected through a load resistance 293 to ground and through an audio filter 2% to the control electrodes of amplifiers in the R. F. and I. F. portions of the receiver. The cathode is connected through a resistance 288 bypassed by condenser 289 to ground, and through resistance 342 to the +3 bus I99. Re-

22 sistances M2 and 238 act as a bleeder to maintain the cathode at sufiiciently high potential to make it inoperative except during reception at overloading levels. During reception of overloading signals the intermediate frequency oscillations are rectified to produce a unidirectional potential across resistance 293 to reduce the amplification of the amplifiers to which it is connected. This is a condition which exists during all positions of control dial 1 except positions 1, l1 and 12. In those positions arm it of the control dial grounds conductor 285, which conductor extends through cable 31, certain contacts of the I. F. relay 39, cable iil, arm 234 of selector switch when in engagement with either of its two lower contacts and conductor 28? to the intermediate point on resistance 288, thereby grounding this intermediate point. This lowers the potential on the cathode. The diode l8l then functions as an ordinary delayed automatic volume control rectifier to produce across resistance 293 a potential varying with the intensity of the received signals and operating to maintain the intensity constant.

Modulated hearing it will be seen from the markings on the operators control dial E that the sector bearing the legend Preset has three other legends Bear. C. W. and Mod. These legends correspond to positions 3, 2 and 1 as indicated in the pilots control box and refer to bearing reception, continuous wave telegraphic reception, and modulated or voice reception. During bearing reception it may be desired to utilize the loop antenna 21 which may be arranged on the craft and rotated for determination of bearing from which the received waves arrive. For this purpose relay 353 is employed and arranged in its deenergized position to connect antenna 23 to the receiver and when energized to connect the loop to the receiver. The operating coil of relay 3l3 may be energized through a circuit including conductor 3M which extends through cables 4!) and 31, and

" loop switch 315 to conductor 592 on which +A voltage exists when the pilots control box has control of the receiver.

. With preset tuning, bearing reception may be had in any band since the band is then determined by the setting or" band selectors A, B, C, etc. Also in manual tuning bearing reception may be had in any band by adjustment of the control dial 1 to positions 4, 5 and t according to the band desired. It is desired, however, during bearing reception to disable the A. V. C. system especially in band i, 0.19 to 0.45 megacycle. With the control dial set to positions 4, 5 and 6 this is automatically efiected as previously described, i. e. in these positions conductor 28% is not grounded by arm l3 and hence the A. V. C. diode is ineffective except on extremely strong signals.

In the sector of the control dial marked A. V. C., where automatic volume control is had, the .19 to .45 rnegacycle band, which appears in the other sectors, is omitted. This is to prevent, or avoid, any possibility of obtaining bearing reception with A. V. C. in this band.

With the control dial 1 set to preset where the band is determined by the reset band i selectors A, B, C, etc. it is likewise desirable to prevent bearing reception in the .19 to .45 megacycle band with A. V. 0., even though the preset sector of control dial i offers a choice of reception with or without A. V. C. This prevention is provided by arm 234 of the selector switch, which in 23 the position shown, corresponding to this band, breaks the circuit of conductor 285 thereby rendering the A. V. C. circuit inoperative. Arm 235 of selector switch in this position connects in circuit the manual volume control 25 irrespective of the position of the control dial I. This is necessary during such bearing reception without A. V. C. to enable the operator to reduce the sensitivity of the R. F. portion of the receiver sufficiently to prevent overloading of the receiver.

Manual volume control As previously mentioned the volume of signal received may be manually varied by the two unicontrolled potentiometers 24 and 25 the first of which is connected as previously described in the audio output circuit and the other of which varies the sensitivity of the R. F. portion of the receiver. This other potentiometer, however, is effective only when the control dial 1 is adjusted to C. W., or modulated bearing reception, i e. to positions 2 to 9 inclusive. In these same positions resistance 203 is connected between the low potential terminal of potentiometer 24 and ground to reduce the effectiveness of this latter potentiometer in varying volume. Thus the variation in volume is principally effected in these positions by potentiometer 25. As potentiometer contact 23 is moved to reduce the sensitivity of the R. F. portion of the receiver potentiometer contact 24 is moved in unison with it to reduce the output audio voltage supplied to the pilots headphones through his own amplifier assuming that the pilots box has control. This may reduce the signal reproduced in the operator's headphones to an undesirably low level, especially since the operators station may be located in the plane at a position where there is greater noise than that at the pilots position. Since the pilot is using only a portion of the audio voltage available across the volume control circuit, the operator may increase the volume of signal in his headphones by operating his volume control knob to positions for greater volume. This does not alter the sensitivity of the R. F. portion of the receiver since his potentiometer 25 is disconnected from the receiver. Thus he may manipulate his volume control to his own satisfaction without affecting the volume of signal heard by the pilot.- The operator may thus hear a signal either greater or weaker, as he desires, than that heard by the pilot except for an extremely weak signal where the pilot may have his volume control at maximum. To reduce the volume in the operator's headphones to its minimum, however, his control dial 1 must be operated to one of positions 1, 10, 11 or 12 in which resistance 200 in the operators control box is shorted by contact arm l2 of switch 1.

Band width control Relay 84 in the intermediate frequency portion of the receiver is arranged to be energized by closure of switch 9 in the control box. This switch bears the legends broad and sharp, corresponding to the two positions of the switch and indicating the resulting frequency band width. This switch, when closed, grounds conductor 322 which extends through cable 31, contacts on relay 39, conductor 322 in cable 40 and thence through winding of relay 84 to the +A conductor 55. Relay 84 may thus change the band width of the intermediate frequency portion of the receiver through connections, not shown.

, sleeve 334.

Fine tuning Fine tuning knob 21 on the control box rotates an arm 28 over a resistance 29, a variable portion of which is connected between conductor 323 and ground. This conductor extends through cable 31, contacts on relay 39, conductor 323 of cable 40 and resistance 324 to the cathode of discharge device 325 in the receiver. This cathode is connected through resistance 326 to the +3 conductor I99 and through resistance 32! to ground. These resistances are proportioned to bias the cathode strongly positive and to render that device substantially non-conductive. By reducing the portion of resistance 29 connected between the cathode and ground this bias can be reduced to render the device conducting to a desired degree. Resistance 32! prevents the voltage on the cathode of device 325 from becoming too high when the circuit of conductor 323 is broken in switching control from one box to the other. This device may be connected as shown in application Serial No. 530,127, filed April 8, 1944, now Patent No. 2,419,869 issued April 29, 1947, by George G. Young for oscillation generators to control the tuning of the local superheterodyne oscillator of the receiver over a narrow range for fine tuning. The application of George G. Young is assigned to the same assignee as my present application.

Figs. 6 and 7 Fig. 6 shows an elevation view of the tuning mechanism assembly. In this figure the respective parts bear the same reference numerals as in the other figures and no additional description is required.

Fig. 7 shows the clamping means by which the disks H8 of the different gear groups 88, 89, etc are clamped to the shaft 92 in adjustable angular position to correspond to the station to be selected. The gear and washers between it and disk 68 are all rotatably mounted on sleeves 333. Similarly gear 61 and Washers between it and disk 68 of the same group are rotatably mounted on The sleeves 333 and 334 of all the groups are positioned end to end along the shaft, the sleeves abutting in each group against the opposite sides of disk 68. Between the groups these sleeves abut against washers 335.

At the end of the shaft is provided a clamping device by which these sleeves are all compressed against the disks 58 and washers 335 to maintain these disks in fixed position about the shaft. This clamping device comprises two members 336 and 331. Member 331 abuts against a stationary bearing member 338 and is provided with a surface 339 oblique to the shaft against which fits a correspondingly oblique surface 342 of member 336. Member 336 may be operated transversely of the shaft by tightening a set screw 345 provided therein thereby sliding surface 342 over surface 339 in a direction at right angles to the shaft. This draws the shaft to the left clamping all of the sleeves between a bearing 344 at one end of the shaft and a spring member 345 at the other.

If it be desired to change the frequency selected by any of the gear groups, for example gear group 88, the set screw 346 is loosened. The disc 68 of group 88 may then be rotated to the position corresponding to the new frequency whereupon the set screw 343 may again be tightened.

This adjustment may best be made by opening switch 350 to deenergize the clutch magnet and permit the shaft 92 to be turned by means of the handcrank until the receiver is tuned to the 25 new station. Then set screw 346 may again be tightened and switch 350 closed. I

While I have shown a particular embodiment of my invention it will, of course, be understood that I do not wish to be limited thereto since many modifications both in the circuit arrangement and in the instrumentalities employed may be made, and I contemplate by the appended claims to cover any such modifications as fall within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, a receiver having remotely controlled means therein for controlling its operation, at least two control stations having respective control means therein for controlling said remotely controlled means, a source of operating potential, at least two switches in each of said stations, electrically-operated circuitconnecting means responsive to operation of said switches in either station to connect said remotely controlled means to the control means in the respective station, to. disconnect it from the control means in the other station, and to energize said receiver from said source, whereby an operator at either station may by operating said switches inhis own station seize control of said receiver irrespective of the condition of said control means in the other station.

2. In combination, a receiver having remotely controlled means therein for controlling its operation, at least two control stations having respective control means therein for controlling said remotely controlled means, electrically-operated circuit-connecting means interposed between said stations and receiver constructed and arranged to connect said remotely controlled means to one and the other of said stations alternatively, and operative means in each station to operate said interposed electrically-operated circuit-connecting means to connect said remotel controlled means to the control means in the respective station, whereby the station in which the said operative means is last operated has control of said receiver.

3. In combination, a receiver having remotely controlled means therein for controlling its operation, at least two control stations having respective control means therein for controlling said remotely controlled means, electricallyoperated circuit-connecting means interposed between said stations and receiver constructed and arranged to connect said remotely controlled means to one and the other of said stations alternatively, operative means in each station to operate said interposed electrically-operated circuit-connecting means to connect said remotely controlled means to the control means in the respective station, whereby the station in which the said operative means is last operated has control of said receiver, a source of operating potential, said interposed electrically-operated circuit-connecting means including means to connect said source to said receiver through the station to which it connects said receiver, and switch means in each station to control the energization of said receiver.

4:. In combination, a receiver, control means in said receiver to control its operation, a plurality of stations, means in each station to control said control means, at least two switches in each station, a source of operating potential, electrically-operated circuit-connecting means responsive to operation of said switches in either station to connect said receiver and said control means 26 to the respective station for control thereby and to connect said source to said receiver through the respective control station, and separate indicating means in said stations to indicate the station to which said receiver is connected and to indicate the energization of said receiver.

5. In combination, a plurality of receivers, a plurality of control stations associated with each receiver, a source of operating potential, a plurality of relays each corresponding with one of said receivers and each constructed and arranged to connect its respective receiver to one and another of the control stations associated therewith alternatively and to connect the respective receiver to said source through the station to which the respective receiver is connected, and means in each control station to operate the respective relay to connect said receiver to the corresponding control station and to control the connection of said receiver to said source.

6. In combination,- a plurality of receivers, a plurality of control stations associated with each receiver, a source of cathode energizing potential, an anode voltage generator, a motor to drive said generator, a plurality of relays each corresponding to one of said receivers and each constructed and arranged to connect its respective receiver to one and another of its associated control stations alternatively and to connect the respective receiver to said source of cathode energizing potential through the station to which the respective receiver is connected, an additional relay for each receiver arranged when operated to connect said motor to said source, and means in each control station to operate the respective one of said first mentioned relays to connect said receiver to the corresponding control station, to connect said receiver to said source, and to operate one of said additional relays to energize said motor to drive said anode voltage generator and connections from said generator to all of said receivers to supply anode operating voltage thereto.

'7. The combination, of a remotely controlled receiver, a plurality of stations to control said receiver, each of said stations having therein a control device to control said receiver when connected thereto, a relay, means to operate said relay, said relay being .arranged in one position to connect said receiver to the control device in one station and in the other position to connect said receiver to the control device in the other station and in either position to connect said receiver to said source through the respective station to which said receiver is connected, means in each station to interrupt the connection of said receiver to said source,'and means in each station to indicate the position of said relay and to indicate, irrespective of the position of said relay, whether or not said receiver is connected to said source.

8. In combination, a receiver having automatic volume control means and automatic frequency selecting means, a remote station to control said frequency selecting means to select any one of a plurality of frequencies, certain of said frequencies lying in different frequency bands, said frequency selecting means including means to select said bands, means in said remote station operative to positions corresponding to the type of reception desired, and means controlled both by said last means at said remote station and said band selecting means at said receiver to disable said automatic volume control means when reception is had in a particular band and to render said automatic volume control means efiective in another band.

9. In combination, a receiver having automatic volume control means and automatic station selecting means, a remote station to control said station selecting means to select any one of a plurality of stations, certain of said stations lying in difierent frequency bands, said station selecting means including means to select said bands, means in said remote station operative to positions corresponding to the type of reception desired, means controlled both by said last means at said remote station and said band selecting means at said receiver to disable said automatic volume control means when reception is had in a particular band and to render said automatic volume control means effective in the other bands, and means at said remote station operable to reduce the sensitivity of said receiver during reception of said one type in said particular band where said automatic volume control means is disabled.

10. In combination, a radio receiver, two remote stations, separate audio channels extending from said receiver to each of said stations, means in each station to vary transmission in the repective channel, means in each station to vary the sensitivity of said receiver, means to render said sensitivity varying means in each station alternatively effective, and means to reduce the effectiveness of the transmission varying means in either station when the sensitivity varying of the same station is effective.

11. In combination, a radio receiver, a remote station, an audio channel extending from said receiver to said station, means at said station to vary transmission through said channel, means unicontrolled therewith at said station to vary the sensitivity of said receiver, means at said station to render said last means alternatively operative and inoperative and to reduce the effectiveness of said first means when said second means is operative.

12. In combination, a radio receiver, two remote stations, each including means to control the operation of said receiver, means to connect said receiver to said control means in said two stations alternatively, separate permanent audio channels extending from said receiver to said stations, each station including means to vary transmission through its respective channel, and said control means in each station including means to vary the sensitivity of said receiver through said connecting means, said transmission varying means and sensitivity varying means in each station being unicontrolled and operative to vary the output from said receiver in like sense, and means in each station to render said sensitivity varying means alternatively effective and ineffective and when effective to reduce the effectiveness of said transmission varying means to reduce volume of output, whereby the output volume in the station, the control means of which is connected to said receiver, is varied principally by said sensitivity control means but the output in the other station may be increased therein by operation of said transmission control without afiecting the sensitivity of said receiver.

KIRBY B. AUSTIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,766,505 Marvel June 24, 1930 1,795,269 Washington Mar. 3, 1931 1,927,260 Erbe Sept. 19, 1933 1,979,588 Vreeland Nov. 6, 1934 2,021,705 Thomas Nov. 19, 1935 2,035,612 Liebreich Mar. 31, 1936 2,093,847 Pruden Sept. 21, 1937 2,099,719 Banning, Jr. Nov. 23, 1937 2,117,638 Walter May 17, 1938 2,190,546 Laube Feb. 13, 1940 2,211,894 Heisner Aug. 20, 1940 2,241,157 Powell May 6, 1941 2,311,168 Gendriess Feb. 16, 1943 

